Agricultural combines are large machines that harvest, thresh, separate and clean an agricultural crop. The resulting clean grain is stored in a grain tank located on the combine. The clean grain is transported from the grain tank to a truck, grain cart or other receiving bin by an unloading auger.
In general, an agricultural combine includes a harvesting platform, a feederhouse, a threshing drum mounted near a concave, sieves, a collection or bulk tank, and various conveyors, such as rotating belts and spinning augers. The harvesting platform gathers and cuts the crop near ground level and directs the harvested crop to the feederhouse, which applies the harvested crop to the threshing drum. The harvested crop is threshed between the rotating threshing drum and the concave separating the grains from the chaff to form threshings, namely, the chaff and the separated grains. The threshings are applied to a cleaning system, which separates the grains from the chaff, applies the grains to the collection or bulk tank that is periodically emptied into a truck, grain cart or other receiving bin by an unloading auger, and discharges the chaff onto the field.
The concave generally includes an array of straight bars that extend parallel to the threshing drum axis of rotation. The curved bars are permanently welded to curved end members. Curved wires, which project through the bars in some concaves and that underlie the bars in other concave designs, extend circumferentially along the concave. A concave of this type forms a grate through which most of the threshed grain and chaff fall onto a collecting assembly where it is directed to the cleaning system of the combine.
A concave must be periodically replaced when the bars wear down or when they are bent or broken by rocks, wire, and other foreign matter that is inadvertently drawn into the combine. Replacing a concave is difficult and time-consuming work, and especially costly when the need arises during a harvest. Accordingly, there is a need in the art for concaves that are easily and inexpensively serviceable without the need for replacement or removal from a combine, are easy to construct and to assemble, that eliminate extended downtimes during harvest, and while at the same time are uniquely designed to favorably influence grain loss and grain damage by favorably influencing grain cracking and fracturing during crop threshing operations.